On the use of biomass size spectra linear adjustments to design ecosystem indicators

Paúl Gómez-Canchong,José M Blanco,Renato A Quiñones

doi:10.3989/scimar.03708.22a

Abstract

Biomass size spectra describe the structure of aquatic communities ataxonomically. The slope ( b ) of the normalized biomass size spectrum (NBSS) is often used as an indicator of the impact of perturbations, such as pollution or overfishing. The NBSS intercept ( a ), has generally been ignored on the basis of a correlation between the NBSS slope and intercept, although this correlation has not been shown to be universal. We assessed whether the NBSS parameters are correlated using: (i) theoretical analysis, (ii) virtual communities randomly generated based only on statistical considerations, and (iii) virtual food webs changing over time following a dynamic bioenergetic model. We also analyzed whether the parameters of the Pareto distribution are correlated or not, using approaches (i) and (ii). We found that when communities change over time there is no single relationship between the two NBSS parameters, due to a dependence on the variation in total community abundance (N). We conclude that to characterize any aquatic system at least two parameters are necessary from the NBSS triad N, a, b . In the case of the Pareto distribution, both N Pareto and b Pareto are necessary.

Highlights

The size spectrum is a two-dimensional graphical representation of ecological pyramids (Cousins 1985) designed to show the biomass distribution across different size classes in a community
In this article we determine, in aquatic ecosystems, whether the slope and intercept of the normalized biomass size spectrum (NBSS) are correlated using the following approaches: (i) theoretical analysis, (ii) virtual communities generated randomly on the basis of only statistical considerations, (iii) virtual food webs changing over time following a dynamic bioenergetic model
We explore the relationship between these two coefficients in previously published empirical size spectra

Summary

Introduction

The size spectrum is a two-dimensional graphical representation of ecological pyramids (Cousins 1985) designed to show the biomass distribution across different size classes in a community. The size spectrum has been recommended as an alternative way to describe the structure of aquatic ecosystems Rodriguez and Mullin 1986, Dickie et al 1987, Gaedke 1993, Blanchard et al 2009, Rochet and Benoit 2011). – List of the different size spectrum coefficients and different processes for which they have been proposed as ecosystem indicators Table 1. – List of the different size spectrum coefficients and different processes for which they have been proposed as ecosystem indicators.

Methods

Results

Discussion

Conclusion